For example, a company producing a color printed material, such as a printing company, periodically performs colorimetry with respect to the color of the printed material, and adjust the color of a printing device printing the printed material, in order to retain the quality of the printed material. In such color adjustment of the printing device, for example, original image data referred to as a color chart is printed by the printing device, and each color of each patch in the printed color chart is measured by a colorimetric device. Then, a color deviation amount between actual measurement values of the colors of each of the patches and target values of the colors of each of the patches is evaluated, and the color of the printing device is adjusted according to the evaluation result.
The color chart is configured of a plurality of color samples referred to as the patch, and in many cases, a plurality of patches are respectively formed with colors (hue, brightness, and saturation), which are different from each other, and are respectively arranged in a predetermined aspect. There are various types in such a color chart. For example, there is a color chart of an aspect in which a plurality of quadrangular patches having various colors are arranged in the shape of a two-dimensional array in all directions. Further, in the color chart of such an aspect, there are various patterns such as a pattern in which the patches are respectively arranged such that random (arbitrary) color arrangement is obtained, according to the contents to be evaluated, or a pattern in which the patches are respectively arranged such that a change in contrasting density between patches adjacent to each other decreases as a gradation. Then, such a color chart is not only prepared by a user by using a color chart preparation tool which is provided by a manufacturer of the colorimetric device, but is also provided from a public institution. Such a color chart actually includes various patterns according to a difference in the shapes, the arrangement, color combination, and the like of the patches.
In contrast, the number of colors used for the color adjustment of the printing device has increased year after year, and according to this, the number of patches arranged in the color chart also increases, and the sizes (the areas) of each of the patches are small.
From such a circumstance, it is not virtually possible to accurately position a measurement portion of the colorimetric device with respect to each of the patches by manual and to perform colorimetry. For this reason, an automatic system is desired in which the positions of each of the patches are automatically measured, the measurement portion of the colorimetric device is automatically matched with the measured positions of each of the patches, and the colors of each of the patches are measured. In Patent Literature 1, a method of importing a two-dimensional color image of a color chart to be measured, of calculating the position of a patch by an image processing method using a computer, of moving a colorimetric head to a determined patch position, and of performing colorimetry with respect to the color chart, is proposed from Gretag-Macbeth AG, Incorporated, as an example of such a system.
In addition, there is a case where chart definition information describing attribute information relevant to the patch, such as of information of the positions of each of the patches or information of the colors of each of the patches, exists, according to a color chart, and thus, there is also a method of acquiring the positions of each of the patches from the chart definition information.
However, in a case where the colorimetric device automatically detects the positions of each of the patches as described above, and performs the colorimetry in the detected positions of each of the patches, there is a case where all of the positions of each of the patches are not capable of being automatically recognized, for example, due to chart failure (abnormality) such as fouling or damage in an actual chart or due to a chart having low contrast between the respective patches. For this reason, a case may occur in which the colorimetric device is not capable of necessarily suitably performing the colorimetry with respect to each of the patches.
On the other hand, even in a case where the colorimetric device acquires the positions of each of the patches from the chart definition information described above, and performs the colorimetry in the acquired positions of each of the patches, there is a case where paper on which the chart is printed expands and contracts, for example, due to a magnification deviation or a printing step of the printing device, such as heat fixing, or due to drying after printing, and the positions of each of the patches in the chart definition information deviates from the positions of each of the patches in the actual chart. For this reason, a case may occur in which the colorimetric device is not capable of necessarily suitably performing the colorimetry with respect to each of the patches.